516. Delivery Mode and Intrapartum Antibiotics Affect the Gut Mycobiome in Newborn Infants and Young Children

Abstract Background The gut mycobiome may have important effects on health. Yet, there is limited data the mycobiome. Previously, we shown that antibiotic exposure at birth markedly alters bacteriome in children. As fungi and bacteria interactions microbiome, hypothesized perinatal antibiotics influence composition of Methods For study, 434 fecal samples were collected birth, 6 months, 18 months age. We extracted DNA from using DNeasy PowerSoil Pro kit. sequenced ITS2 gene analyzed results QIIME2. taxonomy was assigned UNITE database. Results At newborn infants had a low-biomass mycobiome, which developed over time until age months. genus level, transition Candida to Trichosporon Saccharomyces respectively. Unidentified found greater numbers 18-month stool than earlier samples. Alpha beta diversity analyses showed statistically significant differences depending infants. Both delivery mode intrapartum associated with composition. Infants born vaginally abundant their progressed towards dominated by Saccharomyces. Samples via C-section more Malassezia, Hyalotiella Vaginally delivered exposed sp. those unexposed antibiotics. By age, half no group unidentified fungi, but Trichosporon.Figure 1.Taxonomic figures each sample type. Taxa been drawn phylum (innermost level) species (outermost level). Figure 2. Taxonomic type are based mode. 3. vaginal usage Conclusion In this prospective cohort young children influenced both birth. observed Disclosures All Authors: No reported disclosures.